Power percussion tool



April'22,1969 'E.V.A'LEXANDROV 7 POWER PERCUSSION TOOL l of 3 Shet Filed Feb. 11. 1965 April 969 E. v. ALEXANDROV 3,439,755

POWER PERCUSSION TOOL Filed Feb. 11, 1965 Sheet ,3 of s /a l /0 I Ap 1969 E. v. ALEXANDROV 3,439,755

POWER PERCUSSION TOOL Filed Feb. 11. 1965 I Sheet .3 of 3 United States Patent 3,439,755 POWER PERCUSSION TOOL Evgeny Vsevolodovich Alexandrov, Ljubertsy, U.S.S.R., assignor to Institut Gornogo Dela imeni A.A. Skochinskogo, Ljubertsy, U.S.S.R.

Filed Feb. 11, 1965, Ser. No. 431,915 The portion of the term of the patent subsequent to May 31, 1985, has been disclaimed Int. Cl. E21b 1/00; E21c 3/00; B25d 9/00, 11/00, 13/00 US. Cl. 173--119 2 Claims This invention relates to power percussion tools, and more specifically, to power percussion tools for breaking rock and other like hard materials, utilizing an elastic sucker for automatic changeover to idling.

An electrically driven percussion tool utilizing an elastic sucker rigidly connected to the drive and interacting with the striking piston is known from U.S.S.R. authors certificate No. 121,086.

In this tool, the striking piston, while on the working stroke, travels together with the sucker and is in kinematic connection with the drive, the sucker and the piston being disengaged from each other only on the idle stroke.

In this case the drive of the tool fails to have sufiiciently effective protection from surge loading setup in striking the percussion rod during operation of the tool.

Apart from this, for overhead work an ancillary fixing device is necessary to provide for idling by holding the striking piston in the extreme position out of the reach of the sucker.

This invention has for its object to eliminate the above mentioned disadvantages.

Another object of this invention is to provide a simple and dependable power percussion tool having provision for disengaging the striking piston from the drive while on the working stroke, an ancillary device for changeover to idling during overhead work being dispensed with.

According to the present invention, an electrically driven percussion tool utilizes an elastic sucker provided for changeover to idling and rigidly connected to a mechanism converting rotary motion into reciprocating motion, which sucker interacts with the striking piston connected to the tool housing by means of resilient members, designed to disengage the striking piston from the motion converting mechanism, to impart the piston kinetic energy for striking and to hold the piston out of the reach of the sucker when idling during overhead work.

It is proposed that for the resilient members, elastic rods be used made from such a material as rubber or caprone.

This invention provides for protecting the drive of the suggested tool from shock waves and permits polymeric materials to be effectively used for making the main parts of the tool housing.

An embodiment of this invention is described hereinbelow by way of example with reference to the accompanying drawing, wherein:

FIG. 1 is a side view of the tool, parts of which are broken away, the tool being shown in operating position,

FIG. 2 is a side view of the tool in idling operation, and

FIG. 3 is a side view of the tool in a different operating position.

In the drawing there is shown a percussion tool which includes a crank 1 which imparts reciprocating motion to crosshead 3 through connecting rod 2 (the electric motor is not shown).

Circular groove 4 in crosshead 3 accommodates sucker "ice 5 held in place by snap ring 6. Sucker 5 follows the movement of crosshead 3 and intermittently interacts with piston 7 which is connected to housing 9 through resilient members 8.

During its upward travel, piston 7 stretches resilient members 8 as shown in FIG. 1. After sucker 5 disengages from piston 7, the resilient members force the piston downwards, causing it to strike percussion rod 10.

The ends of resilient members 8 are provided with plugs 11 fitting into seats in piston 7 and into seats in the bottom of housing 9.

As crosshead 3 passes the bottom dead centre as shown in FIG. 3, sucker 5 is pressed against the upper face of piston 7 and produces a suction force in a suction space formed therebetween. With crosshead 3 and sucker 5 travelling upwards, the suction pressure acts on piston 7 to raise the same with sucker 5.

Piston 7, being brought upwards by sucker 5, stretches resilient members 8 until the top dead center is reached, at which point the suction space automatically unseals due to the resistance buildup in the resilient members 8, and piston 7, under the action of resilient members 8, travels downwards, thereby striking percussion rod .10.

It will be noted that although the suction space has been shown in the drawing in sucker 5, it may alternatively be placed in the upper portion of piston 7.

The proposed tool may utilize either a crank gear or any other type of transmission, e.g., a cam drive.

During the entire stroke from the top dead center to the point where the percussion rod is met, piston 7 is out of connection with the kinnematic chain.

Steel springs, rubber rods or tubing and similar material may be used for resilient members 8. Rubber rods are most convenient inasmuch as they are not subject to corrosion, they are comparatively light and do not cause any detrimental heating. In addition, rubber more effectively damps out high-frequency oscillations. Sucker 5 may also be made from rubber.

Changeover to idling is effected automatically, no special devices being required for this purpose, since this performance is the inherent property of the system.

When the resistance offered by percussion rod 10 becomes less than the tension of resilient members 8, piston 7 brings percussion rod 10 to the lowermost position and remains there until percussion rod 10 contacts the material being worked. As soon as shoulder 12 of percussion rod 10 leaves housing 9, piston 7 is out of the reach of the sucker as shown in FIG. 2.

It follows that to provide sure changeover to idling, the tension of resilient members 8, with percussion rod 10 moved inward and piston 7 contacting same, must exceed the weight of piston 7 and percussion rod 10.

This condition is necessary for changeover to idling during overhead work.

Since the time during which piston 7 makes its working stroke is practically several times less than that required for crosshead 3 to travel in one direction, the tool needs no dampers or intermediate mases whose functions, as well as changeover to idling, are effected by the resilient members.

The proposed tool does not call for particular precision in making its main parts. To lower the weight of the tool, housing 9 is provided with through slots 13.

Operation of the tool may be intensified by building up excessive pressure inside housing 9, but this will increase the cost and complicate the manufacture of the tool.

2. A tool as claimed in claim 1, wherein said resilient members are elastic rods.

What is claimed is:

1. A power percussion tool comprising: a housing; a drive; a mechanism converting rotary motion imparted by said drive into reciprocating motion and accommodated in said housing; an elastic sucker rigidly connected to said motion converting mechanism; a piston accommodated in said housing for reciprocating movement therein and interacting with said sucker on the upward stroke; resilient members connecting said piston to said housing for disengaging said piston on its working stroke from said sucker, and for imparting kinetic energy to said piston for striking the percussion rod, the resilient members having sufiicient strength to hold said piston out of the reach of said sucker in idling during overhead work.

References Cited UNITED STATES PATENTS 5/1932 Campbell 1731 16 9/1940 Smith 173-116 12/ 1964 Allen et a1. 173-1 19 5/ 1966 Joelson 173116 US. Cl. X.R. 

1. A POWER PRECUSSION TOOL COMPRISING: A HOUSING; A DRIVE; A MECHANISM CONVERTING ROTARY MOTION IMPARTED BY SAID DRIVE INTO RECIPROCATING MOTION AND ACCOMMODATED IN SAID HOUSING; AND ELASTIC SUCKER RIGIDLY CONNECTED TO SAID MOTION CONVERTING MECHANISM; A PISTON ACCOMMODATED IN SAID HOUSING FOR RECIPROCATING MOVEMENT THEREIN AND INTERACTING WITH SAID SUCKER ON THE UPWARD STROKE; RESILIENT MEMBERS CONNECTING SAID PISTON TO SAID HOUSING FOR DISENGAGING SAID PISTON ON ITS WORKING STROKE FROM SAID SUCKER, AND FOR IMPARTING KINETIC ENERGY TO SAID PISTON FOR STRIKING THE PRECUSSION ROD, THE RESILIENT MEMBERS HAVING SUFFICIENT STRENGTH TO HOLD SAID PISTON OUT OF THE REACH OF SAID SUCKER IN IDLING DURING OVERHEAD WORK. 